Currently, there are over 80,000 chemicals in use and approximately 2000 new chemicals are introduced into use every year. Regulatory agencies have recognized the need for alternative toxicological methods and models to decrease the time and expense of current toxicity testing protocols. In association with the National Toxicology Program (NTP), our group is developing C. elegans as an alternative organism for in vivo toxicological testing. Short life cycles, easy and inexpensive maintenance and culturing, and detailed biological knowledge has allowed for the development of rapid, low-cost toxicity tests that readily lend themselves to mechanistic studies of toxicant actions. Because of the evolutionarily conserved nature of the stress-response and other relevant pathways, it is likely that responses elicited in C. elegans will be applicable to understanding similar processes in higher organisms, including humans. This group is part of the National Toxicology Program and within the new Biomolecular Screening Branch. The screening facility is involved in the development of C. elegans as an alternative organism for toxicological testing. Because of the evolutionarily conserved nature of signal transduction and stress-response pathways, it is likely that responses elicited in C. elegans will be applicable to understanding similar processes in higher organisms. There are two major activities of this group: research and development of C. elegans MTS and HTS technologies and participation in the MOU among the NTP, EPA, and NCGC, designated Tox21 (Science 15 February 2008 319: 906-907 DOI: 10.1126/science.1154619). 1. Development of C. elegans medium-throughput screening assays - Protocols for the monitoring of growth, size, reproduction, feeding, and movement have been developed and have been used to test 100 toxicants. Included in the creation of monitoring protocols, statistical analysis routines have been developed specifically for the C. elegans data. We have submitted one manuscript on the feeding assay and are completing additional studies that will be included in manuscripts currently being prepared on the reproduction and growth assays. In collaboration with Chris Portier (LMT), Grace Kissling (EDBP), Marjolein Smith (ASI) we have developed a mathematical model that described C. elegans growth and the effects of toxicants on growth parameters. We are currently generating a collection of green fluorescent protein-based, stress-responsive transgenic C. elegans lines. These lines of C. elegans will be used to identify the ability of toxicants to modulate the activities of signaling and stress-responsive pathways know the affect organism development (e.g., MAPK, p53, tyrosine phosphatase). 2. National Toxicology Program HTS faculty - I am participating in the NTP/EPA/NCGC MOU. We have begun developing protocols to use C. elegans as an HTS test organism. This includes the development of new sampling formats, statistical tools and QA/QC protocols. We are currently testing the NTP 1408 and the ToxCast 320 pesticide actives chemical sets.